Scientific subject (Biology, Chemistry or Physics): theory, problems and data
In the European Baccalaureate you sit one scientific subject as a written examination - Biology, Chemistry or Physics - and the paper is built from three kinds of question: recall and explanation of theory, structured problems, and items based on data or a described experiment (a graph, a table of results, a circuit diagram, a micrograph). Method, units and precise terminology carry marks independently of the final number, so a wrong answer with a correct, visible method still scores.
What is tested
- Knowledge: definitions, laws and models, and the conditions under which they hold - Newton's laws in an inertial frame, ideal-gas behaviour at low pressure and high temperature, enzyme activity limited by active sites.
- Application: multi-step calculations, gradients and intercepts, and interpretation of a result in context.
- Practical and data skills: identifying variables, controls and sources of error, suggesting improvements, judging whether data support the conclusion drawn.
Worked example (physics; the reasoning transfers to chemistry and biology)
A 0.50 kg block is released from rest at the top of a frictionless ramp 2.0 m high, then slides along a rough horizontal floor with coefficient of friction 0.20. Find its speed at the bottom and the distance travelled before stopping.
Reasoning: state the principle first - mechanical energy is conserved on the ramp, so mgh = ½mv². Then v = the square root of (2 × 9.81 × 2.0) = 6.3 m/s to two significant figures. On the floor, friction does work against the kinetic energy: F = μmg = 0.20 × 0.50 × 9.81 = 0.98 N, and Fd = ½mv² gives d = 9.81/0.98 = 10 m. The mass cancels throughout, which is a useful check on the algebra.
Traps
- Units: cm³ to dm³, g to kg, kJ to J. A correct number with the wrong unit is wrong.
- Rounding too early, or quoting eight digits from the calculator; give the symbolic result, then two or three significant figures.
- Skipping the principle: writing 'energy is conserved' or 'n = cV' before the numbers is a marked step.
- 'Suggest why' answered with the data rather than a mechanism; 'the rate rose because the temperature rose' earns nothing.
- Practical items: confusing independent, dependent and controlled variables, or omitting the control needed to attribute an effect.